Ellipsograph



P. O. SOLON Oct. 13, 1953 ELL IPSOGRAPH Filed March 1, 1951 INVENTOR. Phi/6o 0. 50/0/7 ATTOQNEY Patented Oct. 13, 1953 UNITED STATES PATENT OFFICE ELLIPSOGRAPH Philip 0. Solon, Oakland, Calif.

Application March 1, 1951, Serial No. 213,313

6 Claims. 1

The present invention relates to improvements in an ellipsograph and its principal object is to provide a mechanical device adapted to greatly facilitate the drawing of an ellipse to any desired specifications within the range of the instrument.

More particularly it is proposed to provide a device of the character described in which a string is used as a guide for the pencil point, the string being arranged in the form of a loop having both of its free ends secured upon a springactuated drum so that any desired length of loop may be withdrawn from the drum against spring pressure to correspond to the needed length and breadth for the ellipse to be drawn while the drum automatically takes in any slack or surplus string withdrawn in applying the loop.

It is further proposed to provide means forming a unitary structure with the drum whereby two pins may be positioned, first, to correspond to one of the foci and the opposite end of the major axis of the ellipse to be drawn to secure a proper length of loop, and next, to correspond to both fool to allow the loop to be used for guiding a pencil in drawing the ellipse in one continuous sweep.

It is additionally proposed to provide means whereby, after the loop has been properly positioned with respect to the pins with the aid of the loop tensioning means, an unused portion of the loop may be firmly anchored adjacent the drum to prevent any yielding of the loop in response to the pressure of the pencil as the ellipse is drawn.

It is further proposed to provide a mechanical means for drawing geometrical ellipses of any ;size or eccentricity within the range of the instrument by making, with the instrument, measurements from focus to focus and from one focus to the opposite end of the major axis, and there- ;by flXiIlg the exact length of string-loop required for the geometric drawing of the desired ellipse.

Further objects and advantages of my invention will appear as the specification proceeds, and the novel features of my invention will be fully defined in the claims attached hereto.

The preferred form of my invention is illustrated in the accompanying drawing, in which:

Figure 1 shows a perspective view of my ellipso- While I have shown only the preferred form- .of my invention, I wish to have it understood 2 that various changes and modifications may be made within the scope of the claims attached hereto without departing from the spirit of the invention.

Referring to the drawing in detail, my ellipsograph comprises in its principal features a base I, a bar 2 slidable in the base, a pin 3 projecting downwardly from the end of the bar, and a runner I slidable on the bar and carrying a second pin 5, a drum 6, string locking means I, and a string guide roller 8.

The base I may be of any suitable form to give a solid support to the remaining parts, and is here shown as comprising a rectangular block 9 having a fiat bottom face Ill and a central substantially square superstructure II, in which the bar 2 is slidable in a direction transverse to the length of the block. A set screw I2 is adapted for securing the bar in adjusted position.

The pin 3 is threaded into the end of the bar vertically and terminates in a point I3 which, in use, is adjusted to a position substantially on a level with the bottom plane of the base I.

The runner 4 is slidable on the bar 2 between the base and the pin 3 and may be locked in any adjusted position by means of a set screw I4 which is preferably provided with a knurled head. The runner generally comprises a rectangular body portion I5 having a pair of flanges I fi projecting upwardly therefrom and having a second pair of flanges I I projecting downwardly.

The flanges I 6 carry the drum 6 which has the free ends of a looped string I8 secured thereto, the ends being wound upon the drum in the same direction. The drum is provided with a clock spring I ii which tends to rotate the drum in a direction for winding the looped string upon the drum but which allows any desired length of loop to be manually withdrawn while the spring keeps the loop under tension.

The pin 5 which may also be referred to as a back edge proiects downwardly from the runner on the side facing the base substantially to the bottom plane of the base so as to have an easy gliding contact with the drawing sheet in connection with which the device is used. The roller 8 is mounted in the opposite side of the runner, between the flanges I1 and serves to guide the two strands of the loop toward the pin 5 in substantially horizontal direction.

Above the roller the runner carries the locking means .I for the two strands of string, the locking means comprising a pair of spaced rods 20 slidable in the body of the runner in a direction parallel to the bar 2, a short plate 2| carried at one end of the rods and adapted to bear against the face of the runner for locking the strands of the string thereto and a second short plate 22 mounted upon the other ends of the rods and normally urged away from the body of the runner by a spring 23. Thus the two strands of the string are normally looked to the body of the runner, but may be readily released by pressure broughttobeanonthe plate 22.

I use, the; loop 2A of thez -stringusn-normally engaged over the pin 3, and intermediate portions of the two strands are guided over 131167580- ond pin to pass over the guide roller 8 and onto the drum 6. While, for convenience of illustration, the string is shown with [wide clearances.

about the pins, it will be understood that normally the string is underrtensionandezitightly folded upon the pins.

The string I8 is made of non-stretching material, preferably such as is used in a nylon troutiline leader. I

'- In using- -thedevice; the -draftsman first---lays out-theessentialpoints of "th'e= -el-lipse to be drawn, as shown in Figure 3. The -major axis is --:marked bythe points 'W and E, theminor axis by the-points-N==andS;-the center-by the point 0 and the-two foci by the points'LFand RF" left and-rightfocusrf The l'oca-tion'ofgthefoci is ob- =tained by drawing anarc with the radius O'-- W 'about the point this arcintersecting the mag or axis at the foci LF and RF.

I, N ext" the el-lipsog'raph isapplied-, with the pointof the-piir-i resting on RE, rlghtfocus.

-Pressing-on-plate 2-2;-so-as to release the string,

- -the'draftSmanadjusts the runner on'theb'ar 2 tobringthepini over the point ,Wrthat 'is the extreme opposite end of the ,majoraxis: During this adjustment the drum *6 *will feed string or f take-up-'--string" asrrequiredy-keeping' the -loop under tensionat all times. After theproper ad- -justmenthas been madey-thejdraftsman' releases pressure entire-plate 22; causingjtheplate-zl to lock adjacent-portions f" thestring 'upon" the body "Of" the;runner':"*"lhat" portion of the string looped: about the two pins 3 1and"5' .now exactly corresponds to the .length of-string-requir'ed for drawing the-ellipse to the desired; dimensions.

" TWith theistring-firmly'locked bytthe plate 2|,

the dra-ftsmanthen; readjusts" therunner to bring the 'pin- 5; over L-F (leftiocusi :;and locks, it

by means of ""set 'screw l4. This-operation slackens the-available length of, loop. .The

' The ellipse thus formeduis a .trueellipsedrawn v to the original specifications. vIt -passes through vthe points -W and E,.-because-. theztotal. length of stringusedl-in eachoneHhalf-ofz-theioperation is I equal to, the major axis called, fonthestring bei a ing anchored at; one icons and t dOlblQd'ZOPIJOSiQE --'.-,.,the other, :focus to, compensate forvthat: portion of @the. major? axis: extendingamyond; thermfirst 'nfocus..-rit:passes throughzpoints Nzandzs, because qswhem the. pencil crosses-the .vertical ce1'lt'er---1i.rie.

the string formsamequilateraltriangle-each side .ar: "of which aissequal. to one-half: the .length -of the :1: major. :axis,-iand:;finally, the sum or the-distances of 1 any :point from the fooii remains the 'same,

; since the length of the 'used portion of the string 11911131115 the'samethroughout.

I claim:

1. An ellipsograph comprising a bar, means at the rear end of the bar for horizontally supporting the latter, a pin projecting downwardly 5 from the forward end of the bar, a runner slidable on the bar between the pin and the supporting means, a spool revolvable in the runner above the bar, a second spool revolvable in the runner nbelow-rtheubar in parallelirelation to the first 'lflffl pQoLa second pimprnjecting downwardly from the runner rearwardly of the second spool, and

1. a looped string having its ends secured upon the first spool for winding and unwinding operations arland having two strands descending from the said ,spool.on opposite sides of the bar and under- "-neatlr the second spool and around the second j pimwiththeloop 0f the string engaging over the first pin, the first spool being operable for plac- ----ing the looped string under tension, and the runner having means for tightening the two strands mupon the'bodymhereof.

.. 2..1111 ellipsograph comprisingla. .bar, means at he reareend of the. barfor horizontally-supportmg the-13112138132. pin proj ectin'gdownwardlyr from -5:; the-.forwardl-end of: the -bar,-a.runner: slidable on r -.-the:=-bars between-otheapiniaand .the supporting s.:means,i-a.=.spool revolvable in the runners-above theibaigz:arseconde spool irevolvableximthec runner szbelow .:the bar in-parallelarelation tor-the first :spool, asseconde pin projectingsdownwardly from .i -:the :nunner rearwardly of the :second spool, and

-auloopect string. having :its end secured'. upon. the first spool for winding and; unwinding operations andhavingtwo' strandsdescending from the said =-,:spool-1 on :opp'ositell sides of theibar :and: underheath-the second spool and around the second pin with the -loo'p of the stringengaging over the first pin, the first -spool having spring :means for holdin'gthelooped string under tension, and the runnera having means for tighteningthe two 7 -v-strands-upon thebodythe'reof.

F 3. Anellipsographcomprising a bar,:means at a-"the rear-end 'of thebarfor horizontally: supporting-the latterga pin projecting downwardlyi-rom the forward end of the bar, a runner slidable on the bar :between:--the"- pin- 'and' the supporting -means,-'awspool revolvable in the runner above -the-barvasecond spool revolvable intherunner belowthe-bar in parallel relation to -the first spool,---asecondpin projecting downwardly: from thetrunner rearwardly of the second-spool, and adooped' string 'having its ends securedupon the first spool for winding and unwinding operations and-having two stran'ds descending-hem the said spool on opposite side's on the barand underneaththe second s'pool' and-around the second pinwith'-the-loop of 'thestring engaging over the first pin; thefirst spool being operable for placi ing the looped string under" tension, and the -runn'ery-hafing:a pair of=rods 'slidable therein "underneath the bar and plates Supported bythe r rods-forwardly and rearwardly of-- the runner, one of the-plates-beingoperable for -locking the two strands up'orrthe. runner; and the'other plate havingsprinermeans'urging the former plateinto docking position.

..-, A. In;an.., e1lipsogr.aph. of the; character described, a bar, a runner having a 'bodyportion an adapted fozzsliding. .on. the bar. and hayingna pair 7 of upwardly projecting flanges ,above the bar rand savsecondwpair; ofwdow-nwardly rojecting L13 flangesqbelowr the banhalspoolrevolvable between the first pair of fianges-,- a-'second-spoolrevolvableiwbetweeh the seconttpailzoi'fiangestinvparallel Z relation ;to..the.: first-.ispool; a :locpedrstring; having its ends secured upon the first spool for winding and unwinding operations and having two strands descending from the said spool on opposite sides of the bar and underneath the second spool, and means for training the strands emerging from the second spool and the looped end of the string to form a pencil guide for drawing an ellipse, the first spool being operable for placing the looped string under tension, and the runner having a pair of rods slidable therein in parallel relation to the bar and plates supported by the rods forwardly and rearwardly of the runner, one of the plates being operable for locking the two strands upon the runner, and the second plate having spring means urging the former plate into locking position.

5. An ellipsograph comprising a bar, means at the rear end of the bar for horizontally supporting the latter, a pin projecting downwardly from the forward end of the bar, a runner slidable on the bar between the pin and the supporting means and having front and rear faces and having a back edge in the lower rear portion thereof, a spool revolvable in the runner above the bar and having a portion projecting forwardly beyond the front face of the runner, guide means on the runner below the bar and for- Wardly of the back edge and substantially in vertical alinement with the projecting portion of the spool, and a looped string having its ends secured upon the spool for winding and unwinding operations and having two strands descending from the front portion of the spool on opposite sides of the bar and past the guide means in spaced relation to each other, and converging thence toward the back edge and carried around the same, with the loop of the string engaging over the pin.

6. In an ellipsograph of the character described, a bar, a runner having a body portion adapted for sliding on the bar and having a pair of upwardly projecting flanges above the bar and a second pair of downwardly projecting flanges below the bar, a spool revolvable between the first pair of flanges and having a forwardly presented discharge edge, a guide between the secand pair of flanges in parallel relation to the spool and in vertical alinement with the discharge edge of the spool, a looped string having its ends secured upon the spool for winding and unwinding operations and having two strands descending from the discharge edge of the spool on opposite sides of the bar and passing the guide in spaced relation to one another, and means for training the strands emerging from the guide and the looped end of the string to form a pencil guide for drawing an ellipse.

PHILIP O. SOLON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,373,056 Crowder Mar. 29, 1921 1,724,738 Stossel Aug. 13, 1929 2,256,011 Ballou Sept. 16, 1941 FOREIGN PATENTS Number Country Date 67,269 France May 9, 1865 191,645 England Jan. 18, 1923 

